In its extreme stage of coloration it differs from ludovicianus in paler and purer color; the ash of back lighter; the under parts brilliant white, not decidedly plumbeous on the sides as in the other, and without so great a tendency to the usual obsolete waved lines (noticed distinctly only in winter or immature birds); the axillars bluish-white, not plumbeous. The white of wings and tail is more extended; the hoary of forehead and whitish of scapulars more distinct. The bristles at base of bill somewhat involving the feathers are black, forming a narrow frontal line, not seen in the other. The most striking difference is in the rump and upper tail-coverts, which are always appreciably and abruptly lighter than the back, sometimes white or only faintly glossed with plumbeous; while in typical specimens of ludovicianus these feathers are scarcely lighter at all, and generally more or less varied with blackish spots at the end. The legs and tail are apparently longer, the latter less graduated. These differences are, however, most appreciable in specimens from the Middle and Western Provinces. Those from the Western States, east of the Missouri River, as far north as Wisconsin, are more intermediate between the two, although still nearest to the Rocky Mountain bird
as described; the back darker, the rump and axillars more plumbeous, the sides more bluish. There is little doubt that the examination of series from the States along the Mississippi will show a still closer resemblance to typical C. ludovicianus, and that the gradation between the two extremes will be found to be continuous and unbroken. It therefore seems reasonable to consider them all as one species, varying with longitude and region according to the usual law,—the more western the lighter, with longer tail. The only alternative is to suppose that two species, originally distinct, have hybridized along the line of junction of their respective provinces, as is certainly sometimes the case. The approximation in many respects of coloration of the Shrikes of the Pacific coast to those of the South Atlantic States is not without its importance in the discussion of the subject. However it may be, it is necessary to retain the name of excubitoroides, as representing, whether as species or variety, a peculiar regional form, which must be kept distinctly in mind. The comparatively greater size of the bill in the Cape St. Lucas specimens is seen in other species from this locality (No. 26,438 of adjacent figure).
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The intensity of the black front in this species varies considerably, being sometimes very distinct, and again entirely wanting. This may probably be a character of the breeding-season, the dulness of black anterior to the eye and the lighter color of the bill having a close relationship here, as in other species, to maturity, sex, and season.
Habits. This variety was first described from specimens obtained in the territory of the Hudson’s Bay Co. Richardson states that it was not found farther north than the fifty-fourth degree, and there only in the warm and sandy plain of the Saskatchewan. Its manners, he says, are precisely similar to those of the borealis, feeding chiefly on the grasshoppers, which were very numerous on the plains. Mr. Drummond found its nest in the beginning of June, in a bush of willows. It was built of the twigs of the Artemisia and dry grass, and lined with feathers. The eggs were six in number, of a pale yellowish-gray color, with many irregular and confluent spots of oil-green, mixed with a few of smoke-gray.
Mr. Ridgway met with it, in his Western explorations, in all localities, but most frequently among the Artemisia and in the meadow-tracts of the river valleys. It is also seen on all parts of the mountains, among the cedar groves, localities in which the ludovicianus is said never to be found.
Dr. Cooper describes this bird as abundant in all the plains-region of California, but not as far as the Columbia River. South of latitude 38°, they reside all the year. They were abundant about Fort Mohave all winter, and nested as early as the 19th of March in a thorn-bush. They had young early in